The present invention relates to an evaporative type medium condenser of an outdoor apparatus of an air conditioning system without the utilizing of conventional cooling fins especially relates to an evaporative condenser which a plurality of streamline cross section bare metal tubes are used for the medium coils to tack the place of conventional round tube coils for highly increasing the evaporative efficiency by the bare streamline tubes themselves to omit the using of cooling fins so as to thoroughly avoid the possibility of deposit dirt and sediment on the coil tubes between conventional cooling fins to provide the improvement of a long life time and convenient for maintenance and cleaning therefore.
The air conditioning system is a very important installation now in daily life of human been, as to save the energy source, a problem of how to improve the E.E.R. of an air conditioning system will be a target of the designers and producers to be reached, therefore the type of heat dissipation for cooling the medium coils is improved from air cooling to water cooling and then tendered to evaporative cooling.
Theoretically, 1 Kg of water absorbs 539 Kcal of latent heat while evaporated, but absorbs only 30 Kcal of heat while the temperature of 1 Kg cooling water be raised 30xc2x0 C. as a maximum value that a water cooling system can be achieved, the deferent ratio is 18 times.
However, in now a day the most of so called evaporative cooling system in market are not a real evaporating system but a combination of air cooling water cooling and evaporative cooling. Because:
Firstly, there are still conventional round tubes used for medium coils. As shown in FIG. 1A, which a wind flow W blows faced to a leading edge A of a round sectional tube 110 with a layer of water film thereon, divided into two flows around the surface of the tube 110 respectively to point F and Fxe2x80x2 through two opposite point D and Dxe2x80x2 of a diameter of the tube 110 as shown by arrow headed lines and then directly blows to a tube 110xe2x80x2 of next row of the coils. In that case, a lot of drawbacks will be happened as:
1. The wind flow W dose not blows over a rear portion of the curved surface of an arc FEFxe2x80x2 (E is the end edge of the tube110) it""s a kind of waste.
2. The eddy currents will be occurred behind the rear edge E and also a windless area will be happened thereat to offer a poor effect to the next row tube 110xe2x80x2.
3. Essentially the evaporation efficiency is not fully developed while the wind flow W blows over the water film on the surface of curved area ADF and ADxe2x80x2Fxe2x80x2 is under a condition of normal atmosphere pressure.
Secondary, there are still cooling fins used in high density as 13xcx9c17 piece per inch, in which there will be water layers full filled the interval between two adjacent fins but no water films occurred on the fins for evaporating therefore it is not a real evaporative system in fact.
FIG. 1B shows a streamline cross sectional tube 120 according to the present invention to instead of the conventional round tube for medium coils which a wind flow W blows headed to a leading edge A of a large head portion of the streamline tube 120 and divided into two opposite path around the surface of tube 120 passing through the diameter DDxe2x80x2, respectively to a gradual reduced rear portion of curve DE and Dxe2x80x2Exe2x80x2, in which, according to theory of aerodynamics, the wind flow W will blows still around the surface DE and Dxe2x80x2Exe2x80x2 of the reduced area closely, further more, there a rapid acceleration will be occurred to provide a large negative pressure thereon, therefore as a water film kept continuously on the surface of the streamline tube 120 in a wind flow W, it will be evaporated easily even at a room temperature under an extra low pressure (large negative pressure) and a large amount of latent heat of water evaporation (539 cal for evaporating 1 gr of water) will be absorbed from the gaseous state medium in the tube 120 to produce a low temperature thereat, in which a low critical pressure of a medium compressor is need for condensing the low temperature medium from gaseous state into liquid state so as to save energy for improving E.E.R. therefore.
Practically a streamline cross section can be combined with two different ellipses by half and half, which FIG. 2A shown a first ellipse xe2x80x9cAxe2x80x9d taken from a projection view of a tilt cutting to a round tube R of a diameter D with an obtuse angle xcex1, while FIG. 2B shows a second ellipse xe2x80x9cBxe2x80x9d taken from a projection view cutting to a same round tube R of a diameter D with an acute angle xcex2, and FIG. 2C is a cross sectional view of a streamline tube combined with a left half of ellipse xe2x80x9cAxe2x80x9d and a right half of ellipse xe2x80x9cBxe2x80x9d, in which the preferable value of tilt angle xcex1 and xcex2 used in the present invention are;
xcex1=60xc2x0xc2x15xc2x0, xcex2=25xc2x0xc2x15xc2x0
In FIGS. 2A, 2B and 2C, actually xcex1=60xc2x0, xcex2=25xc2x0.
Further more, a streamline cross section is different from a cross section of a symmetrical aerofoil, which a symmetrical aerofoil section tube as shown in the figures of the prior arts of U.S. Pat. No. 3,885,936 and Japan patent 63,096,490 there a rear end of the tube is a narrow sharp angular form, while a rear end of a streamline cross sectional tube of the present invention as shows in FIG. 1B is characteristically formed of an end portion of an ellipse with a convex curve to avoid a narrow sharp angular edge inside the tube, a narrow sharp angular form inside the tube may do nothing for a regular heat exchanger as claimed in the foresaid prior arts, but there will be a serious drawback for using to a medium condenser, because there will be a large amount of pressure drop occurred due to a high friction loss when the medium flow runs in the narrow sharp angular portion inside the tube, in which , an extra power of a medium compressor is needed for recovering the loss of pressure drop, the E.E.R. then can not be improved therefore.
FIG. 3 shows another embodiment of a streamline tube may used in the present invention which a streamline tube 120 has a tail fin 122 extended from a rear end edge for increasing the heat dissipation rear therefore.
The present invention is a mew design according to the theory of aerodynamics to solve all the foresaid drawbacks of the conventional medium condensers.
Therefore, a main object of the present invention is to provide a medium condenser composed of a plurality of streamline cross section bare metal tubes to improve a high evaporative heat dissipation efficiency according the theory of aerodynamics.
Another main object of the present invention is to provide a medium condenser without the using of conventional cooling fins to avoid the deposit dirt and sediment on the coil tubes between conventional cooling fins so as to maintain a long life time therefore.
Still another object of the present invention is to provide a medium condenser without conventional cooling fins for saving the cost and work of manufacturing, and convenient for maintenance and cleaning.